Silver alloy film, flat panel display, and sputtering-target material used for forming the silver alloy film

ABSTRACT

Provided is a silver alloy film for which good properties of corrosion resistance, heat resistance and adhesiveness are required in thin-film electronic components such as a flat panel display, various semiconductor devices, a thin-film sensor and a magnetic head, a display device having the silver alloy film, and a sputtering-target material for forming the silver alloy film. The silver alloy film consists of, by atomic %, 0.1 to 1.0% Si, 0.1 to 0.7% in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of all the additive elements to Ag is not more than 1.5%.

BACKGROUND OF THE INVENTION

The present invention relates to a silver alloy film for which good properties of corrosion resistance, heat resistance and adhesiveness are required in thin-film electronic components such as a flat panel display, various semiconductor devices, a thin-film sensor and a magnetic head, to a display device having the silver alloy film, and to a sputtering-target material for forming the silver alloy film.

PRIOR ART

In recent years, a silver film especially used for electronic components has been of note, which has an advantageous property of low electrical resistance. However, there are problems that such a metal film made of Ag is poor in adhesiveness to substrates, heat resistance property and low corrosion resistance property while it has a satisfactory property of low electrical resistance.

On the other hand, in recent years, a flat panel display (herein below referred to as FPD) has rapidly been widely used as an alternative display to a conventional cathode-ray tube. The FPD includes, for instance, a liquid crystal display (herein below referred to as LCD), a plasma display panel (herein below referred to as PDP), a field emission display (herein below referred to as FED), an electroluminescence display (herein below referred to as ELD), and an electrophoresis type display used for an electronic paper or the like. When Ag is applied to a wiring film in the FPD, there arises a problem of film exfoliation during processing because of low adhesiveness to a glass substrate or a resin substrate, a resin film, and a metal foil such as a stainless steel having high corrosion resistance property.

Further, when Ag is exposed to heat (e.g. in a heating process) during manufacturing various electronic components, it suffers grain growth resulting in deteriorated smoothness of a film surface. Depending upon a material type of a substrate and a heating atmosphere, there will occur an aggregation of the film to lose a film continuity resulting in increased electrical resistance. Moreover, because Ag is poor in corrosion resistance property, a silver film formed on the substrate has problems of occurrence of tarnish after only about one day exposure to air, and a substantial increase in electrical resistance or film exfoliation due to corrosion by chemicals used in manufacturing the electronic components.

In order to solve the problems mentioned above, it has been proposed to form an silver based thin film having excellent conductivity and optical characteristics by using a silver alloy target containing not less than 0.1 atomic % of Cu (see, for example, JP-A-8-260135).

It has also been proposed to use a reflection type conducting film which is made of a silver alloy containing Pt, Pd, Au, Cu or Ni and which is formed on an adhesive layer (see, for example, JP-A-11-119664).

There has also been proposed a metallic material for electronic components made of a silver alloy containing 0.1 to 3.0 wt % of Pd and 0.1 to 3.0 wt % in total of Al, Au, Pt, Cu, Ta, Cr, Ti, Ni, Co or Si (see, for example, JP-A-2001-192752).

According to some patent publications (see, for example, JP-A-2001-102325 and JP-A-2002-266068), there has been known a silver alloy film with low electrical resistance, which contains not more than 25 wt % of Ru, and not more than 25 wt % of Cu or Au.

There has also been known a reflection wiring electrode made of a silver alloy containing any one of Zn, Ni, Sn and In, in combination with a transition metal (see, for example, JP-A-2004-002929).

SUMMARY OF THE INVENTION

However, when such proposed metal elements are added to Ag, obtained silver alloys have increased electrical resistance. Thus, it can be said that no silver alloy film, which has compatible properties of low electrical resistance, adhesiveness, corrosion resistance, heat resistance and patterning property, has been proposed until now. Specifically, with regard to additive elements, for example, such as transition metals including Ta, Cr, Ti, Ni and Co, or metalloids (e.g. Al), silver alloys containing those have increased electrical resistance, wherein more than 1 atomic % of the additive element(s) makes the silver alloys to have resistivity exceeding 5 μΩcm which is a currently required value. In the case of additive Cu being one of related elements of Pd, Pt and Au which are noble metals, it does not so increase electrical resistance of silver alloys, but causes a problem of heat resistance.

Thus, an object of the present invention is to provide a silver alloy film which has properties of low electrical resistance, heat resistance, corrosion resistance, adhesiveness to a substrate, and patterning property; to provide a sputtering-target material for forming the silver alloy film; and to provide a flat panel display which has a high definition.

The present inventors made every efforts to solve the above problems, and found that it is possible to obtain a desirable silver alloy film by adding a combination of selected elements into Ag, thereby improving the silver alloy film in heat resistance and corrosion resistance properties without substantially deteriorating the low electrical resistance which inherently Ag has, and further improving the silver alloy film in adhesiveness to a substrate and patterning property, whereby attaining the present invention.

According to a first aspect of the present invention, there is provided a silver alloy film consisting essentially of, 0.1 to 1.0 atomic % of Si and 0.1 to 0.7 atomic % in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of the additive alloying elements is not more than 1.5 atomic %.

According to one feature of the invention, the silver alloy film may comprise 0.1 to 0.5 atomic % of Si, 0.1 to 0.4 atomic % in total of at least one element selected from the group consisting of Cu, Ti and Ge, wherein a total amount of the additive elements is not more than 0.8 atomic %, the balance being substantially Ag.

According to another feature of the invention, the silver alloy film is a wiring film having the above chemical composition for a flat panel display.

According to still another feature of the invention, the silver alloy film with the above chemical composition has resistivity of not more than 5 μΩcm.

According to a second aspect of the present invention, there is provided a flat panel display comprising the silver alloy film as a wiring film, which has the above chemical composition.

According to a third aspect of the present invention, there is provided a sputtering-target material for forming a silver alloy film, which consists essentially of, 0.1 to 1.0 atomic % of Si and 0.1 to 0.7 atomic % in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of the additive alloying elements is not more than 1.5 atomic %.

According to one feature of the invention, the sputtering-target material for a silver alloy film may comprise 0.1 to 0.5 atomic % of Si, 0.1 to 0.4 atomic % in total of at least one element selected from the group consisting of Cu, Ti and Ge, wherein a total amount of the additive elements is not more than 0.8 atomic %, the balance being substantially Ag.

The silver alloy film of the present invention comprises a combination of Si and at least one element selected from the group consisting of Cu, Ti and Ge, thereby exhibiting compatible properties of low electrical resistance, heat resistance property, corrosion resistance, adhesiveness to a substrate, and patterning property. Thus, it is useful for a wiring film of a flat panel display requiring high definition and fast response, so that it is industrially very valuable. The sputtering-target of the invention may be preferably used for forming the silver alloy film having the above properties.

PREFERRED EMBODIMENTS OF THE INVENTION

A feature of the present invention resides in finding of an alloy composition most suitable to compensate the inferior properties of Ag, which are adhesiveness, corrosion resistance and heat resistance while keeping the low electrical resistance of Ag itself as low as possible.

In general, when a silver film is formed, although it has low electrical resistance, as afore mentioned, there will arise various problems during manufacturing a flat panel display (such as a liquid crystal display) as an electronic component. More specifically, there will occur growth or aggregation of film when heated, whereby the surface of the film becomes more rough, and/or it has voids. And when the film is heated in the atmosphere, the film surface discolors to cause an increase in electrical resistance. Under such a technical background, according to the present invention, it was found most effective to add a combination of Si and at least one element selected from the group consisting of Cu, Ti and Ge into Ag, which elements are selected from various existing elements, in order to improve heat resistance property, corrosion resistance property, adhesiveness to a substrate and patterning property when photo-etching, while keeping low electrical resistance, as compared with a silver film. Most preferably, the amounts of the additive elements to Ag are 0.1 to 1.0 atomic % of Si, and 0.1 to 0.7 atomic % of at least one element selected from the group consisting of Cu, Ti and Ge, wherein the total amount of the additive elements is not more than 1.5 atomic %.

Here, there will be provided a description on the reason why the elements of Si, and the at least one element selected from the group consisting of Cu, Ti and Ge are preferred, and on the additive amounts thereof.

While the additive elements in silver increase the electric resistance of silver, heat resistance and corrosion resistance properties are improved more effectively as the additive amounts increase. Thus, in order to improve the above defects of silver while keeping the low electrical resistance, the additive amounts of the above elements have to be carefully adjusted in order to obtain satisfactory advantageous effects with required minimum amounts of the additive elements.

At first, an effect of a single additive element of Si in silver will be described. An effect of the additive Si is to improve corrosion resistance and heat resistance properties of a silver alloy film. In order to obtain the improvement effect by Si, a minimum Si amount of 0.1 atomic % is required. But, when the Si amount exceeds 1.0 atomic %, the silver alloy film may have excellent corrosion resistance and heat resistance properties while increasing the electrical resistance. Preferably, the Si amount is not more than 0.7 atomic % in order to obtain lower electrical resistance of the silver alloy film. The alloy film comprising a single additive element of Si is poor in adhesiveness to a substrate, such that there will occur exfoliation of the film in a cleaning process when manufacturing a flat panel display, for example. In such a case, it is also noted that when the film is subjected to patterning process, exfoliation of the film is further promoted to confront with difficulty in producing a uniform wiring pattern. Thus, such a single additive Si is insufficient for improving the adhesion property of the film.

Thus, an earnest investigation was performed to seek an effective element(s) to be added to Ag in combination with Si for improving adhesiveness, and it was found that an additive element(s) selected from the group consisting of Cu, Ni, Al, Ti, Zr, Mn, Fe, Co and Ge is effective for improving the properties of the silver alloy film. One or more of the elements (i.e. Cu, Ni, Al, Ti, Zr, Mn, Fe, Co and Ge) may be selected for the purpose of the invention. In order to obtain the desired effect, it is necessary to add Si and one or more of the elements (i.e. Cu, Ni, Al, Ti, Zr, Mn, Fe, Co and Ge) to Ag, respectively, at least by 0.1 atomic %. On the other hand, when the elements exceed 0.7 atomic %, the results are an excessive increase of electrical resistance.

A key aspect of the present invention resides in a combined addition of Si and the above effective element(s) to Ag, wherein Si is effective for improvement of corrosion resistance and heat resistance properties, and wherein one or more of the elements (i.e. Cu, Ni, Al, Ti, Zr, Mn, Fe, Co and Ge) is effective for improvement of film adhesiveness and heat resistance property, whereby attaining compatible properties by virtue of all the additive elements.

A minimum additive amount of the respective element as mentioned above is not less than 0.1 atomic % in order to obtain the improvement effects of the film. Thus, the minimum total amount of the additive elements is 0.2 atomic %. In the present invention, a combined addition of a trace amount of the above optional elements to Ag further inhibits grain growth of the film, and can form a high density silver alloy film with a smooth surface. This reduces voids in the film, inhibits an increase in electrical resistance, so that a silver alloy film can be formed with improved corrosion resistance property by virtue of inhibition of corrosion at grain boundaries, and further improved adhesiveness by virtue of reduced stress in the film.

With regard to the upper limit of an additive amount of the respective element in the case of a combined addition of the above elements, the Si amount is set to be not more than 1.0 atomic %, the total amount of the one or more elements selected from Cu, Ni, Al, Ti, Zr, Mn, Fe, Co and Ge is set to be not more than 0.7 atomic %, and the total amount of all the additive elements is set to be not more than 1.5 atomic %, because it is hard to obtain a silver alloy film having low electrical resistance, in combination with corrosion resistance property, heat resistance property, adhesiveness, and patterning property when the additive amounts exceed the above values.

Thus, it is possible to obtain a silver alloy film having excellent properties, which is optimal for a wiring film of flat panel displays, by specifying the additive amounts of Si and the one or more elements selected from Cu, Ni, Al, Ti, Zr, Mn, Fe, Co and Ge such that the Si amount is 0.1 to 1.0 atomic %, the total amount of the selection elements is 0.1 to 0.7 atomic %, and the total amount of all the additive elements is not more than 1.5 atomic %. In order to obtain the silver alloy film having further lower electrical resistance, more preferably, the Si amount is 0.1 to 0.5 atomic %, the total amount of the selection elements is 0.1 to 0.4 atomic %, and the total amount of all the additive elements is not more than 0.8 atomic %. Among the selective elements, Cu, Ni, Ti and Ge are preferable, and a combination of Si and one or more of these elements makes the silver alloy film to have excellent improvement effects of adhesiveness, heat resistance property, and corrosion resistance property, and easily to have low electrical resistance. Further, one or more of the additive elements of Cu, Ti and Ge can realize lower electrical resistance, adhesiveness and good heat resistance property, and thus they are most preferable when added in combination with Si.

Although a ground why the additive elements according to the invention are effective in improving the film properties is not clear, the following is a supposition thereof. Normally, in the film formed by sputtering or the like, additive elements are dissolved in the alloy matrix in a supersaturated state to restrain migration of atoms thereby making the film to have fine crystal grains. Metalloid Si in Ag increase the electrical resistance of the silver alloy film little, and restrains the crystal-grain growth thereby improving heat resistance property of the film. In the elements of Cu, Ni, Al, Ti, Zr, Mn, Fe, Co and Ge, some of them have a solid solubility range to Ag, and the others are isolated from Ag. On the other hand, some of them have a solid solubility range to Si, and the others form compounds with Si. For these reasons, there are formed compounds, and simple substances of the Si and the other elements by the addition of Si and the other elements to Ag, which the compounds and the simple substances precipitate at grain boundaries to restrain aggregation of Ag, thereby improving adhesiveness of the film to a substrate. Further, it is believed that the combined addition of Si and the other elements to Ag restrains migration of Ag atoms and corrosion at grain boundaries in a heating process, thereby improving heat resistance and corrosion resistance properties.

Further, Cu, Ge and Ti are preferable among the additive elements other than Si in order to obtain the silver alloy film having low electrical resistance and good heat resistance property, when they are added to Ag in combination with Si.

Cu does not form a compound with Ag, and has a solid solubility range to Ag at high temperature, but is isolated easily at low temperature, whereas it has a wide solid solubility range to Si and forms a compound with Si.

Ge also does not form a compound with Ag, and has a solid solubility range to Ag at high temperature, but is isolated easily at low temperature, whereas it forms a complete solid solution with Si.

Ti also has a solid solubility range up to 5 atomic % to Ag near a temperature of the melting point of Ag, and has a reduced solid solubility range at low temperature. Ti forms a compound with Si. Thus, when the silver alloy film is formed by sputtering, for example, the additive elements exist in the film in a non-equilibrium solid state, but with a lapse of time or by heat treatment at a low temperature of not higher 300° C., Cu, Ge and Ti are easily isolated from the Ag matrix while entraining Si, whereby realizing low electrical resistance. From the above, it is believed that an addition of one or more of Cu, Ge and Ti to Ag in combination with Si can realize a silver alloy film having the lowest electrical resistance, good adhesiveness and good heat resistance property.

Further, when Cu, Ge and Ti are added in combination with Si even in such a small additive amount as to keep the low electrical resistance, they have an effect that white clouds and white points hardly occur by heat treatment at about 250° C. Thus, they are the most preferable additive elements.

When Si and noble metals of Au, Pd, Pt and Ru are added to Ag, the electrical resistance of the silver alloy does not increase so much, while corrosion resistance property can be improved. Therefore, the addition of the noble metals in combination with the aforementioned elements is also effective. However, because the noble metal elements are expensive, there is a cost problem in commercial base. Regarding Au, when it is added to Ag in an amount exceeding 0.5 atomic %, a residue is liable to occur during etching, and when the Au amount exceeds 1.0 atomic %, a much amount of residue is produced resulting in deterioration of the patterning property, contrasting to the invention silver alloy which is an inexpensive material and excellent in patterning property.

As a substrate used in forming the silver alloy film according to the invention, a glass substrate or a Si wafer is preferred, because these substrates have excellent processing stability when manufacturing a flat panel display, and by heating in forming the silver alloy film according to the invention, they provide the silver alloy film with lower electrical resistance and higher adhesiveness than the film formed at a room temperature.

According to the invention silver alloy film, it is possible to obtain as low resistivity as not more than 5 μΩcm, even as formed by sputtering, while it is possible to obtain lower electrical resistivity by subjecting the substrate to heat treatment. Particularly, by adjusting an additive amount of the elements and heat-treating the substrate at a temperature of not lower than 250° C., it is possible to obtain a silver alloy film having low electrical resistance of not more than 3 μΩcm. Thus, the invention silver alloy film is suitable for a wiring film of an organic EL display and a liquid crystal display of which production process comprises forming polysilicon TFT through a heating treatment with utilization of a glass substrate and a Si wafer.

Further, the invention silver alloy film is preferably applied to a reflection film since it has excellent reflectivity.

While even conventional Ag—Cu alloys and Ag—Pd alloys can have low electrical resistance by heat treatment, they are poor in adhesiveness and heat resistance property when the electrical resistance thereof is low. Thus, it can be said that there has been no such an alloy film that satisfies as many properties as the invention silver alloy film.

When forming the invention silver alloy film, the sputtering process with utilization of a target material is optimal, according to which process it is possible to form a film having substantially the same chemical composition as a target material, whereby the invention silver alloy film can be stably formed. Thus, the present invention is also directed to a sputtering-target material for forming the silver alloy film, which has the same chemical composition as the silver alloy film.

While there are various methods for producing a target material, any methods are acceptable so long as a product target material can have a high purity, a uniform structure and a high density which are generally required to the target material. For instance, it can be produced by casting a molten metal, which is adjusted to a predetermined chemical composition by means of a vacuum melting process, into a metallic mold, and subsequently subjecting the casting to forging, rolling and so on thereby obtaining a tabular form, and to machining thereby finishing the work to obtain a target material. In order to obtain a target material having a more uniform structure, a rapidly solidified ingot, which is produced by a spray forming process (a droplet deposition process), may be used, or the powder sintering process may also be used.

Regarding the invention sputtering-target material used for forming the silver alloy film, it may contain unavoidable impurities which are gaseous components of oxygen, nitrogen and carbon, and an alkali metal, an alkaline earth element, a transition metal and a metalloid provided that they do not impair the advantages of the invention.

For instance, the gaseous components of oxygen, carbon and nitrogen should be as little as not more than 50 ppm in content, respectively, Cr, Mo and W be not more than 100 ppm in content, Zn and Sn be not more than 500 ppm in content, and an acceptable purity of the sputtering-target material is not lower than 99.9 mass %.

In addition, for a substrate used for manufacturing a flat display element, a glass substrate or a Si wafer is suitable as described above, but any material is acceptable which is capable of having a thin film formed thereon by sputtering, for instance, a resin substrate, a metal substrate, a resin foil and a metal foil.

The invention silver alloy film for electronic components, preferably has a film thickness of 100 to 300 nm in order to provide stable electrical resistance, because the film with a thickness of less than 100 nm increases electrical resistance and forms an easily changeable surface morphology of the film due to the surface scattering effect of electrons since the film is thin, whereas the film with a thickness of more than 300 nm has low electrical resistance but tends to be easily exfoliated due to the stress in the film, needs a long time for forming the film, resulting in lower productivity.

EXAMPLE

A plurality of raw materials were prepared so that the respective material has substantially the same chemical composition as a desired chemical composition of a silver alloy film containing additive elements and Ag. Each of the prepared raw materials was melted in a vacuum melting furnace, and was cast to obtain a silver alloy ingot. Thereafter, the ingot was formed into a tabular shape by plastic working, and the work product was machined to obtain a sputtering-target material having a diameter of 100 mm and a thickness of 5 mm. With utilization of the target material, a silver alloy film with a thickness of 200 nm were formed on a flat glass substrate or on a Si wafer by a sputtering process. A pure silver film was also prepared by the same way as the silver alloy film. With regard to the thus prepared films including the pure Ag film, those electrical resistance were measured by a four-probe method.

Further, in order to evaluate how film properties change between pre- and post-processes needed to produce an electronic component such as display units, the pure silver film and the silver alloy films as produced by the above method were examined on the basis of the following conditions.

For evaluation of heat resistance property, the pure silver film and the silver alloy films were heat-treated at 250° C. for two hours in vacuum, respectively, and thereafter the resistivity of the respective films were examined.

For a corrosion resistance test, the pure silver film and the silver alloy films were exposed to a temperature of 85° C. in a humidity of 90% for 24 hours, respectively, and thereafter the resistivity of the respective films were measured.

In order to evaluate the adhesiveness of the films, gridiron cut lines at intervals of 2 mm were provided to the heat-treated pure silver film and silver alloy films, respectively, and an adhesive tape was affixed onto the respective films surface and peeled off. The squares left on the substrate were expressed by an area rate, and was evaluated as adhesiveness.

For the evaluation of patterning property, a resist, OFPR-800 made by TOKYO OHKA KOGYO CO., LTD. was applied by spin coating on the respective metal films of which heat resistance property was evaluated, was exposed to ultra-violet rays with the use of a photomask, was developed with an organic alkali developing solution NMD-3 made by Tokyo OHKA KOGYO CO., LTD. to form a resist pattern, which was then used to perform etching with a mixed solution of phosphoric acid, nitric acid, acetic acid and water, to form a pattern of the metal films. Exfoliated metal film of the pattern, the shape of the edge and residue in the periphery were observed with an optical microscope, and the metal film having no film exfoliation and no residue was determined to be excellent. The evaluation test results according to the above method were shown in Table 1. TABLE 1 Resistivity (μΩ cm) after as after corrosion Specimen Chemical Composition film- heat resistance Adhesiveness Patterning No. (atomic %) formed treatment test (%) property Type 1 Ag 2.7 1.8 3.2 50 C Comparative Specimen 2 Ag—0.05Si—0.3Cu 3.0 2.3 3.2 65 C Comparative Specimen 3 Ag—0.3Si—0.05Cu 2.9 2.3 3.2 60 C Comparative Specimen 4 Ag—0.5Si—0.3Cu 3.0 2.2 3.0 85 A Invention Specimen 5 Ag—0.5Si—0.15Ni 3.0 2.3 3.1 75 A Comparative Specimen 6 Ag—0.5Si—0.3Ge 3.0 2.2 3.0 85 A Invention Specimen 7 Ag—0.8Si—0.5Ni 3.8 3.1 3.8 85 A Comparative Specimen 8 Ag—0.5Si—0.4Al 3.5 2.9 3.1 85 A Comparative Specimen 9 Ag—0.5Si—0.4Ti 3.1 2.4 3.0 80 A Invention Specimen 10 Ag—0.3Si—0.3Cu—0.1Ge 2.9 2.5 2.9 80 A Invention Specimen 11 Ag—0.3Si—0.3Zr—0.1Mn 3.6 3.0 3.4 80 A Comparative Specimen 12 Ag—0.8Si—0.8Cu 5.1 4.2 5.3 80 A Comparative Specimen 13 Ag—1.1Si—0.7Ni 5.9 4.5 5.6 75 A Comparative Specimen 14 Ag—0.9Pd—1.7Cu 4.2 3.0 5.2 65 C, B Comparative Specimen 15 Ag—3.0Cu 6.2 5.0 6.5 65 C Comparative Specimen 16 Ag—0.3Cu—0.4Au—0.3Ru 8.5 6.2 6.5 65 B Comparative Specimen 17 Ag—0.5Si—0.3Cu 3.2 2.4 3.2 80 A Invention Specimen 18 Ag—0.3Si—0.4Ti 3.0 2.5 3.0 80 A Invention Specimen (*Note 1: A = excellent, B = occurrence of residue, C = occurrence of film exfoliation) (*Note 2: The pure silver film and the silver alloy films of specimen Nos. 1 to 16 were formed on a glass substrate, respectively. The silver alloy films of specimen Nos. 17 and 18 were formed on a Si wafer, respectively.)

A pure silver film (No. 1) has low specific resistance of 3.0 μΩcm or less after film-forming, and has a further reduced resistivity after heat-treatment. However, the film is shown to have low adhesiveness, and poor patterning property due to exfoliation of the film. A conventionally proposed silver alloy film (No. 14) containing Pd and Cu added to Ag is shown to have a specific resistivity equal to that of the silver alloy film according to the present invention, but has low corrosion resistance property, shows an increased resistivity after corrosion resistance test, has low adhesiveness, and produces residue in etching.

A silver alloy film (No. 15) containing Cu added to Ag is shown to have low heat resistance property and low adhesiveness. A silver alloy film (No. 16) containing additive elements of Cu, Au and Ru to Ag has high resistivity and forms residue in etching.

On the other hand, silver alloy films (No. 4 to 11 and No. 17 to 18) containing Si in combination with Cu, Ni, Ti, Zr, Al, Mn and Ge added to Ag, are shown to have as low resistivity as 5 μΩcm or lower after film-forming, keep low specific resistivity even after heat-treatment and after a corrosion resistance test, have substantially improved adhesiveness and have excellent patterning property. The improving effect is enhanced by increased additive amounts, and the effect of each element becomes apparent in an additive amount of 0.1 atomic % or more. However, when the additive amount of Si exceeds 1.0 atomic %, the additive amounts of Cu, Ni, Ti, Zr, Al, Mn and Ge exceed 0.7% atomic %, and the total additive amounts exceed 1.5 atomic %, the film does not provide resistivity of 5 μΩcm or less. It is also shown that among additive elements besides Si, elements Cu, Ni, Ti and Ge show little increase of the value of resistivity, and that in order to obtain the value of resistivity of not more than 3 μΩcm, the additive amount of Si is preferably not more than 0.5 atomic %, the additive amount of Cu, Ni, Ti and Ge is preferably not more than 0.4 atomic %, and the total additive amount is preferably 0.8 atomic %. It is also shown that as an element to be added in combination with Si, elements Cu, Ge and Ti are more preferable because of showing a lower value of resistivity while keeping adhesiveness.

In addition, specimen Nos. 17 and 18 having a silver alloy film formed on a Si wafer, as is apparent from Table 1, show a similar result as the specimens having the silver alloy film formed on a glass substrate. 

1. A silver alloy film consisting essentially of, by atomic percent, 0.1 to 1.0% Si, 0.1 to 0.7% in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of all the additive elements to Ag is not more than 1.5%.
 2. A silver alloy film according to claim 1, which is of a wiring film for flat panel displays.
 3. A silver alloy film according to claim 1, which has a resistivity of 5 μΩcm.
 4. A silver alloy film according to claim 1, consisting essentially of, by atomic percent, 0.1 to 0.5% Si, 0.1 to 0.4% in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of all the additive elements to Ag is not more than 0.8%.
 5. A silver alloy film according to claim 4, which is of a wiring film for flat panel displays.
 6. A silver alloy film according to claim 5, which has a resistivity of 5 μΩcm.
 7. A flat panel display comprising a wiring film made of a silver alloy consisting essentially of, by atomic percent, 0.1 to 1.0% Si, 0.1 to 0.7% in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of all the additive elements to Ag is not more than 1.5%.
 8. A flat panel display according to claim 7, comprising a wiring film made of a silver alloy consisting essentially of, by atomic percent, 0.1 to 0.5% Si, 0.1 to 0.4% in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of all the additive elements to Ag is not more than 0.8%.
 9. A sputtering-target material used for forming a silver alloy film, consisting essentially of, by atomic percent, 0.1 to 1.0% Si, 0.1 to 0.7% in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of all the additive elements to Ag is not more than 1.5%.
 10. A sputtering-target material according to claim 9, consisting essentially of, by atomic percent, 0.1 to 0.5% Si, 0.1 to 0.4% in total of at least one element selected from the group consisting of Cu, Ti and Ge, and the balance of Ag and unavoidable impurities, wherein a total amount of all the additive elements to Ag is not more than 0.8%. 